Development and Adoption of Early AASHO Design Criteria

1998 ◽  
Vol 1612 (1) ◽  
pp. 26-33 ◽  
Author(s):  
Jerome Hall ◽  
Daniel Turner
Keyword(s):  
Design Parameters ◽  
Design Criteria ◽  
Adoption Process ◽  
Horizontal Curve ◽  
Highway Design ◽  
Initial Development ◽  
Design Processes ◽  
Blue Book ◽  
Curve Design ◽  
Independent Design

The conception, development, and adoption of early AASHO highway design criteria are documented. Examining the early efforts states used to select a design vehicle and develop horizontal curve design criteria illustrates why AASHO’s leadership was necessary. AASHO’s slow and somewhat haphazard criteria development, and the disparity from state to state, demonstrated the need for a national consensus in highway design parameters. AASHO’s role in providing these criteria is outlined through its initial development of policy booklets, followed by its 1954 publication of the landmark Blue Book. The processes by which nine states adopted the AASHO guidance are briefly reviewed. In several cases, the AASHO policy was embraced immediately, and in others it was accepted slowly as states clung to their independent design processes and only gradually updated their design criteria. A few simple conclusions are drawn about the development and adoption process, particularly as it may relate to tomorrow’s highway design criteria.

Three-Dimensional, Probabilistic Highway Design

2008 ◽  
Vol 2060 (1) ◽  
pp. 10-18 ◽  
Author(s):  
Mohamed Sarhan ◽  
Yasser Hassan
Keyword(s):  
Reliability Analysis ◽  
Probabilistic Approach ◽  
Three Dimensional ◽  
Design Parameters ◽  
Horizontal Curve ◽  
Vertical Alignment ◽  
Highway Design ◽  
Side Slope ◽  
Sight Distance ◽  
Stopping Sight Distance

The potential usefulness of reliability analysis has recently been stressed in many engineering applications. Given the variability in the design parameters, a reliability-based probabilistic approach is well suited to replace the current deterministic highway design practice. However, progress in this regard is generally slow. In this study, the reliability analysis was used to estimate the probability of hazard (POH) that might result from insufficiency of sight distances. As an application, the available sight distance was checked against required stopping sight distance on an assumed road segment. Variation of the design parameters was addressed with Monte Carlo simulation using 100,000 sets of design parameters based on distributions available in the literature. A computer program was developed to use these sets of design parameters to calculate the profiles of available and required stopping sight distances in two- and three-dimensional projections as well as the profile of POH. The approach was applied to a horizontal curve overlapping with flat grade, crest curves, and sag curves in a cut section where the side slope would restrict the sightline. The analysis showed that the current deterministic approach yields very conservative estimates of available and required stopping sight distance, resulting in very low POH. The application example also showed the change of POH with the change of vertical alignment parameters.

Safety Effects of Horizontal Curve Design on Motorcycle Crash Frequency on Rural, Two-Lane, Undivided Highways in Florida

2017 ◽  
Vol 2637 (1) ◽  
pp. 1-8 ◽  
Author(s):  
Chunfu Xin ◽  
Zhenyu Wang ◽  
Pei-Sung Lin ◽  
Chanyoung Lee ◽  
Rui Guo
Keyword(s):  
Negative Binomial ◽  
Design Parameters ◽  
Negative Binomial Regression Model ◽  
Horizontal Curve ◽  
Random Parameters ◽  
Crash Frequency ◽  
Curve Design ◽  
Time Space ◽  
Curve Radius ◽  
Motorcycle Crashes

The association between horizontal curve design (e.g., radius and type) on rural, two-lane, undivided highways and motorcycle crash frequency is not well documented in existing reports and publications. This study aimed to investigate the effects of design parameters and associated factors on the occurrence of motorcycle crashes with consideration of the issue of unobserved heterogeneity. A random-parameters negative binomial regression model was developed on the basis of data on 431 motorcycle crashes, which were collected on 2,179 horizontal curves along two-lane, undivided highways in Florida for 11 years (2005 to 2015). Four normally distributed random parameters (i.e., logarithm of curve radius, reverse curves, pavement condition, and rough pavement indicator) were identified to represent their heterogeneity caused by unobserved factors over time, space, individuals, or some combination thereof. The major conclusions are the following: ( a) an increase in curve radius, on average, significantly and near-logarithmically reduced motorcycle crash frequency on rural, two-lane, undivided highways (this effect was more significant when the curve radius was less than 2,000 ft); ( b) 74.8% of reverse curves tended to reduce motorcycle crash frequency on rural, two-lane, undivided highways (for the remaining 25.2%, the effect had an opposite effect; on average, the likelihood of motorcycle crashes on reverse curves decreased by 39%); ( c) the crash modification function (CMF) for curve radius on rural, two-lane, undivided highways was established, given the radius of 5,000 ft as the baseline, as a power formula, CMF = (radius/5,000)-0.208.

Modeling Safety Effects of Horizontal Curve Design on Injury Severity of Single-Motorcycle Crashes with Mixed-Effects Logistic Model

2017 ◽  
Vol 2637 (1) ◽  
pp. 38-46 ◽  
Author(s):  
Chunfu Xin ◽  
Zhenyu Wang ◽  
Chanyoung Lee ◽  
Pei-Sung Lin
Keyword(s):  
Logistic Model ◽  
Injury Severity ◽  
Unobserved Heterogeneity ◽  
Mixed Effects ◽  
Severe Injury ◽  
Horizontal Curve ◽  
Random Parameters ◽  
Horizontal Curves ◽  
Curve Design ◽  
Motorcycle Crashes

Horizontal curves have been of great interest to transportation researchers because of expected safety hazards for motorcyclists. The impacts of horizontal curve design on motorcycle crash injuries are not well documented in previous studies. The current study aimed to investigate and to quantify the effects of horizontal curve design and associated factors on the injury severity of single-motorcycle crashes with consideration of the issue of unobserved heterogeneity. A mixed-effects logistic model was developed on the basis of 2,168 single-motorcycle crashes, which were collected on 8,597 horizontal curves in Florida for a period of 11 years (2005 to 2015). Four normally distributed random parameters (moderate curves, reverse curves, older riders, and male riders) were identified. The modeling results showed that sharp curves (radius <1,500 ft) compared with flat curves (radius ≥4,000 ft) tended to increase significantly the probability of severe injury (fatal or incapacitating injury) by 7.7%. In total, 63.8% of single-motorcycle crashes occurring on reverse curves are more likely to result in severe injury, and the remaining 26.2% are less likely to result in severe injury. Motorcyclist safety compensation behaviors (psychologically feeling safe, and then riding aggressively, or vice versa) may result in counterintuitive effects (e.g., vegetation and paved medians, full-access-controlled roads, and pavement conditions) or random parameters (e.g., moderate curve and reverse curve). Other significant factors include lighting conditions (darkness and darkness with lights), weekends, speed or speeding, collision type, alcohol or drug impairment, rider age, and helmet use.

Effects of Biomimicry on Architecture

2020 ◽  
Vol 3 (2) ◽  
pp. 106
Author(s):  
Elif Gizem Yetkin
Keyword(s):  
Research Methodology ◽  
Architectural Design ◽  
Environmentally Friendly ◽  
New Age ◽  
Design Parameters ◽  
Integration Model ◽  
Design Processes ◽  
City Life ◽  
Road Map ◽  
Basic Features

The sociological, psychological and physiological problems experienced by humanity, which have been exposed to dark offices, high flats and city life far from nature, have been strikingly exposed with researches. In addition, the nature-based design approaches that emerged due to the need to meet the need of humanity for nature and the desire to return to nature have taken their place among the design parameters of the new age in architecture However, concepts where biology and design come together have emerged. Biomimicry is a discipline that explores the best ideas for design processes by imitating nature. It takes all the ecological needs that users expect from architecture directly from the nature. It provides an integration model with the nature that people yearn for, and also creates a model that takes the solutions created by nature in architectural designs as an example. In this period of architectural design turning to nature, biomimicry has the feature of being a pioneer of a new architectural trend by providing designers with a different view of nature. The main purpose of this study is to determine the application areas and basic features of the biomimicry approach in architecture and to create a road map for designer architects. To achieve this goal, a research methodology has been designed to achieve two objectives. First, it will carry out an in-depth research on biomimicry, architecture and environmentally friendly designs with existing literature studies. Secondly, listing the biomimicry designs applied in architecture and classifying them according to their ecological gains to the building. As a result, a guide will be created for the designer architects to provide ease in producing more efficient buildings.

Evaluation of a Unique Chamber for a Beef Carcass Cleaning Unit1,2

1982 ◽  
Vol 45 (1) ◽  
pp. 19-22 ◽  
Author(s):  
M. E. ANDERSON ◽  
R. T. MARSHALL ◽  
W. C. STRINGER ◽  
H. D. NAUMANN
Keyword(s):  
Red Meat ◽  
Full Scale ◽  
Design Parameters ◽  
Design Criteria ◽  
Basic Design ◽  
Water Droplets ◽  
Beef Carcass ◽  
The Doors

Our objective was to develop basic design criteria for use in fabricating a functional chamber for a red meat carcass cleaning unit. Emphasis was placed on eliminating the doors. A model carcass cleaning chamber was constructed to test effects of selected design parameters on direction and velocity of airflow. Based on data from the tests using the model, a full-scale chamber with no doors was designed, fabricated, and installed in a commercial packing plant for testing. The air moves into the chamber at both the entrance and the exit. This movement of air into the chamber prevents water droplets entrained in the air from escaping into the slaughtering area and causing condensation on the walls and roof.

Safety Evaluation for the Highway Alignment with 3D Visual Simulation

2012 ◽  
Vol 182-183 ◽  
pp. 1131-1134
Author(s):  
Xiao Jia Chen ◽  
Yi Cheng Luo
Keyword(s):  
Safety Evaluation ◽  
Visual Simulation ◽  
Horizontal Curve ◽  
Current Standard ◽  
Highway Design ◽  
Standard Requirement ◽  
Sight Distance ◽  
Real Scene ◽  
A Minor ◽  
Highway Alignment

In the current highway design, poor coordinate of the alignment has a great effect on the sight distance which would increase the danger and difficulty of driving. For this reason, safety checking for highway alignment is required by the current standard. In this paper, 3D simulation technique was used to model the real scene of driving. Based on the concept of the preview sight distance (PVSD), two typical coordinates of alignment in practice were discussed. Although the current standard requirement is met, it is demonstrated that the alignment in the location of a minor horizontal curve and combination of a tangent with a circular curve could still provide driver confusing information. Some recommendations were suggested so as to improve the highway alignment design.

Fundamental Design Issues of Brush Seals for Industrial Applications

2002 ◽  
Vol 124 (2) ◽  
pp. 293-300 ◽  
Author(s):  
Saim Dinc ◽  
Mehmet Demiroglu ◽  
Norman Turnquist ◽  
Jason Mortzheim ◽  
Gayle Goetze ◽  
...  
Keyword(s):  
High Speed ◽  
Failure Modes ◽  
Industrial Applications ◽  
Operating Conditions ◽  
Design Parameters ◽  
Design Criteria ◽  
Seal Design ◽  
Brush Seal ◽  
Brush Seals ◽  
As Stress

Advanced seals have been applied to numerous turbine machines over the last decade to improve the performance and output. Industrial experiences have shown that significant benefits can be attained if the seals are designed and applied properly. On the other hand, penalties can be expected if brush seals are not designed correctly. In recent years, attempts have been made to apply brush seals to more challenging locations with high speed (>400 m/s), high temperature (>650 °C), and discontinuous contact surfaces, such as blade tips in a turbine. Various failure modes of a brush seal can be activated under these conditions. It becomes crucial to understand the physical behavior of a brush seal under the operating conditions, and to be capable of quantifying seal life and performance as functions of both operating parameters and seal design parameters. Design criteria are required for different failure modes such as stress, fatigue, creep, wear, oxidation etc. This paper illustrates some of the most important brush seal design criteria and the trade-off of different design approaches.

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